Electrical measuring instrument.



` INSLIRUMHNT.

APPLIUA'HOH rum JM; m1.

H0 MGDEL.

VOLTS MAINS.

No. 769,984. y PATBNTED SEPT. 1.3,1904y y {F.DUNCAN. g ELECTRICAL MBASURING INSTRUMENT.

APPLICATION Hlm) JUNI; 26,1901.

H0 MODEL. 3 sums-SHEET 2.

NU. 739,991, PATENTBD SEPT. 1s, 1904.

T. DUNCAN, BLECTPJQAL MEASURING INSTRUMENT.

PPLIOATION FILED JUNE 26.1901.

NO MODE] 3 SHEETS-SHEET 3 IMMMMMME N i i l i i i i ings` when the current in the working circuit i UNITED STATES "r'iioMAs DUNCAN, or

ciiioiioo, iiiLiNois.

ELEQTFiiCAL MESURENG iNSTRUMENT.

SPECIFICATIGN forming part of Letters .'Pa tent No. 769,984i ated September 13, 1904.

Appiicnnn sie". im 2e, 1961.

Serial Kc. 68,099. (No model.)

Be it known that'i, Tiioriiis DUNCAN, a citi- 1 zen of the United States. residing at Chicago. in the county of Cook and State of Iliinois havenrented a certain new and useful lmprovement iirEirctrieiil Measuring Instruments, (Case No. 2.) of which the followingis r. full, clear. concise, andexact description, reference being had to the. accompanying drawings, forming part of this specification.

My invention relates to means for indicating; the phiisc difference between .the current and pressure in alternating-current circuits, and has t'or its object the provision of means whereby .such difference in phase may be de termined by a Single measuring element, and whereby it may be determined whether the current leads or lugs with respect to the pres- E sure. To accoinpiish this object, I provide a i current heid-winding producing magnetism that varies in phase with the magnetism of the current in the working.,r circuit 9md :issocinte with this` current-\'.'inding wo pressurewindings, which enact with the enrrent-winding to eti'ect the movement of a measuring needle to indicate the extent the current maiv 'lag or lead with respect to the impressed pressure.

In practicing my invention I ,preferably provide prek'sure-windings that produce fields in quadratiue with the impressed pressure, the fields due to these pressure-wint."ings being one hundred and eighty degrees iipartin phase. The magnetism diie to the currentwinding is displaced ninety degrees from the magnetism due to either of the pressure-windis in phase with the impressed electromotive force. To .secure :i movement of the measuring element or indicating-needle to indica-te a variation in phase between the. current and impressed electroinotire force, the said current-winding is made movable withrespcct to 5' the. pressure-windiiigs, the current-winding itself being preferably rotatable and carrying,r` the indicating-needle. The current-winding is so disposed upon its shaft that when 'the' current und pressure in the werking circuit g are in phase thecurrent-windinglies midway between the pressure-windings and is unaf- 1 whether or not the current leads or ings and to what extent. l preferably associate with the ind icuting-needle a scale, upon which scale marks are provided indicating in degrees 'the iagging or leadingr angles. This scale thus marked will also indicate to those skilled in the art the power factor of 'the systeincthat is, the scale-marks indicating ten degrees lag or lead correspond to the power factor of .9848, the scale-marks 2G correspond to the power factor of .9397, the scale-marks "30 correspond to the power factor of .866. the scale-marks 40 "correspond to the power factor of .766, the scale-marks 50 correspond to the power factor .t5-128, the scalemarks correspond to the power factor E'of .5, the scale-umriss 70" correspond to thev power factor of .342, the scale-marks 50' the scale-marks 9() corrcspond to the power factor of O.

Means are provided whereby the measurements of the instrument Will not be modified` by a variation in current and pressure; for

which purpose 1 prefer to maintain the inagnetisin d ue to cach winding constanmwhi'ch re' .suit may be accomplished by including in clrcuit with the pressure-windings a resistance that may be varied to conform'to the varying current and pressure, more resistance being included when the pressure in the working circuit increases and the resistance being cut out as the pressure decreases, while a similar resistance is included in circuit with the current-winding, the resistance being increased upon an increase in current in the working circuit and decreased ppon a decrease of thc current in' the working circuit.

. correspond to the power' factor of .1736, and

ion

i i f i i e W i g 1 willexplain my invention more fully by t. il

' grani illustrating the pbase relations of the magnetic tieids diie to the pressure-windings.

Fig. 4 illustrates :i modification of the instrument constructed in accordance with my invention. the instrument there shown being associated with a circuit including an alternating-currcnt generator.

Like parts are indicated bysimilar characters of' reference throughout the di'erent figurcs.

The pressure-windings land 2 are preferably stationary; while the current-winding 3 is prcferablymounted upon a rotatable shaft. 1, upon which winding, preferably by being attached to the shaft, is secured a pointer :3, that registers with a iiieasuring-scalc '5, with the middle pointof which the pointer is adapted to register when the current and pressure in the working or transmission circuit are in plase. The scale 6 may be provided with a sei-ics of scale-marks that may serve to indicate when the needle registers therewith the extent to'whicli the current and pressure are gut of phase. The scale-marks are symmetricalliv arranged with respect to the central point with which the needle 5 registers when the current. and pressure in the working circuit are in phase. the cu rreiit when laggingin phase causinga deflection of the necdle toward the right to indicate. the angle of lag, while the current in leading causes a deflection ot' the needle 5 toward the leftto indicate the angle that the current leads. The current-coil 3 thus occupies a medium position when the current and pressure in the work-circuit are in phase, to secure which adjustment of the coil a balanced condition must be brought about between the field d ue tlieretoand the ficldsof the pressurewindings 1 and 2. This balanced condition is brought! about'by having the magnetism due to the current-coil 3 differing ninety degrees from the magnetism due to the coils 1 and 2.` As the currentand pressure in the workingcircuit vary in phrase, obviously the phase of the magnetism due to the current-winding 3 varies with relation to the magnetism 'due to the windings 1 and 2, whereby the axis of the magnetism of winding 3 is caused to approach one or the. other ot' the magnetic axes diie to the windings 1 and 2.l 'lhe winding 1 may produce a field thu* lags ninety degrees hehind the impressed pressure.` the line A A indicating the magnetic axisot' this field.' The winding 2 produces a magnetic field that leads ninetiiy degrees with resp ct to the impressed pressure, the line B B' indicating the axis of this tieid. The line C C' indicates the axis of the magnetic ield due to the winding 3. If the cui-rent in the inajn circuit lags, the magnetism() dueto tile winding 3 also lags. thereby approaching .the magnetism A .-i' in phase and causinga niovcinentof the winding 3 and the pointer 5 in a contraf clockwise direction to indicate upon the scale 6 the. angle of lag.

l main circuit leads with respect to the impressed pressure, the magnetism C C' ap'- preaches` the magnetism B B' in phase, thereby causing a clockwise movement ot' the pointer 5 to indicate upon the. scale 6 the angle at which the current leads the pressure. In order that any small lag or lead will not send the pointer tothe end of t-lie scale, there must be some restraining torque applied to the coil 3 and its associated point-er f. This re.- strainiiig torque ma" he applied wholly or partially by the springs 23 23. whichalso serve to conduct the current to the. coil 3, and this torque may 'be added to by4 the efi'ect of gravity upon some part ot' the movable mem' bei'. as uponthe pointer in the case of F ig 1 and the coil 3 in VFig. 4t. The combined action of the magn'etizations of the coils 1 and 2 upon the coil 3 is :bus opposed by this restraining torque, whereby a balance is ob' tained, indicating the phase di'erence. as desired. Any well-known means may be employed for securing magnet-ic fields in the windings of the' meterhaving the desired phase displacements. ln Figs'. 1 and 4 I have illustrated a transformer 7, having its primariT included in bridge of the workingcircuit and its secondary connected 'in circuit with both pressure windings or coils 1 and 2. The current-winding 3 is supplied from a transformer S. whose primary winding is included in one of the main conductors and whose secondary winding is included in a closed local circuit with the said current-winding. In Fig.

4 l have illustrated the coils 1 and 2 prpvidedf respectively, with secondary coils 9 and 10 in eluded in circuit with ladjusting-inductance. 11 and 12, while inductanee 13 and 14 is included in series with the windings 1 and 2. To secure aphase displacementof one hundred and eighty degrees, tlie terminals of these windings 1 and 2 a reversed with respect to each other. windings 1 and 2 included serially in the same circuit with the secondary ot' the transformer 7. This circuit seriallg.1 includes the winding 15 of a transformer 16.- the remaining winding 17 of the transfoi'urer'l being in parallel with the secondary of the' transformer' 7' and the windings 1 and An adjusting resistance 18 is included in circuit with the trans-- lf the current in the In Fig. 1 I have illustrated the- ICO IIO.

4o leading current and its phase relation to the 60 both mcssure-windings,and means associated Q, the said windings` are reversed with respect i to cur-h other. The effect is illustrated in Fig. where O E indicates the innxo- .-;cd a elwztroniotitjc force. The coil i7 induces in the coil i." s secondary current 0 (i, ulrich lwhcn combined with the current O Fah'eady {lowing in the coil produces a resultant current O H. By reversing one of the wind- .ings we haven current O H in one winding io aude current OAH' in the other winding proj dueing magneticlields displaccdone hundred end eighty degrees. 1n order to maintaiuj the proper magnetizing effects of the windf ings o tlmzneter. compensating', means` in this l r5 instance in the form oi rhcostats 19 20, are i employed, the resistance of rheostat 19 being i inciudcd in circuit with the pressure-windl ings, while the rbc-estat 20 is in circuit with thecurrent-windings. Reading-scales 2l and l zo 2i-2 are associated with the rcsistances 19 and Q0. upon which are volt vand ampere scales. Whenever tlie instrument of my invention is to be operated, the. arms of the rheostats 19 and 20 are moved to points along,r the "dingz5 seules corresponding respectively to the pressure and current, so that theiiiagnetizing effects due to thc windings of the instrument are the same irrespective of* thonet-ual pressore and current in the distributing system. 3o `When the current andvpressure in the Work or transmission circuit are in phase, the phase of the iicld due to the current-windingr 3 is displaced ninety degrees from the fields due to windings 1 und 2, as heretofore set forth, and n change in phase in the current of the work or transmission circuit causes a corresponding change in the phase of thc magnetism of the current-winding und e dccction of the: needle 5 to indicate e lagging or pressure, all as heretofore setforth.

\\hilel have herein shownand particularly 'described the preferred embodiment of my invention, it is obvious that changes may readily be made without departing from the spirit thereof` land I do not wish` therefore, to be limited to the precise disclosures herein set forth; but,

Having thusdescribed my invention` I claim 5o new ainidcsire to secure by Letters Patent l. The combination with es vstem of alternating-current distribution, of a measuring instrument for indicating the lag or lead of the current, having pressure-windings producing fields out'o phase with the impressed electroinotive force and with each other; a 'current-winding producing u lield varyingin phase. with vthe current ofthe system, und diftering from those of the tields produced by with the said windings. whereby the magnetizations of the exciting-coils are maintained constant, substantially as described.

2. The combination with an alternating-cur.

b5 rent system of distribution, of an instrument fordctcrminiiw thc blowing or'lcinlinc huso zrwn of'thc current. in rcspc o the pressure. the

said instrument huringoue prcssurwnhiding, priruxcing u field lagging ninety degrees behind the impressed pressure of the system, n. 7o sccomlpressurc-winding producing' u iield d isplaccdmic hundred und eight)v degrees from the field produced by thc aforesaid pressurewinding: the current-:rimiing producing a field varying in phase with the phuse ot' the 7 current of the system and rheost-nts iissom'ated with the said windings, whereby the umgnctizatious ot the exciting-coils are maintained constant. substantially as described. 3. lnemeasuring instrument for indicuting 8o the lag or lead of thc current, with respect to the pressure in e system of alternating-current distribution, the combination with pressure-windings producing iieids out of phase with the impressed electroiuotive force, und with euch ozhcr. of a current-winding prof' ducing a field varying in phafe with the cur. rent of the sysm, and dilfcring in phase from both pressnre-windings, said currentwinding being subject to thefaction of both 9o pressure-windings, und means whereby th mugnetizutions of the exciting-emissie maintsincdconstunt, substantially as described.

1. 1n anieasuringinstrument for indicatingl the lag; or lend of the current, with respect to 95 the pressure in a system or' ultcrnuting-cu.- rentdistribution, the combination with pressure-windings producing fields out of phase. with the impressed electromotire force, and

with euch other, of a current-winding pro ducing u field varying in phase with the current of the system, and differing zu phase .from both pressure-windings, said currentwinding being subject to the action of both pressurelwmdings, and means whereby the ratio bet-Ween the magnetizetions oiA the exciting-coils may be maintained, substantially as described.

5. In a measuring instrument for indicating' the lug or lead of 'the current, with. respect to l 19 the pressure in a system of ultcrnating-current distribution, the combination with pressure-windings producing fields out et' phase with the impressed electromotire force. and with euch other. of a current-winding pro- H5 ducing' a iicldvarying in phase with thc current of the system, avid differing in phase from both pressure-windings, seid current winding-being subject to the action ot' both pressure-windings, und means for preventing modification in the o eration of theinstrument by changes in te load condition, substantially as described.

1n witness whereof I hereunto subscribe my name this23d day of May, A. D. 1901.

lTHOMAS DUNCAN.

Vt'itnesses:

. GEORGE L. Online` A HERBERT l?. Oennorr 

